Method and apparatus for assembling exterior automotive vehicle body components onto an automotive vehicle body

ABSTRACT

The present invention generally relates to a method and programmable apparatus for the assembly of body components to an automotive body that has undergone a progressive series of framing and welding steps so as to produce a structurally rigid body frame, termed a body-in-white. More specifically, this invention relates to creating a new net locating scheme (X-Y-Z coordinate system) for a body-in-white to direct associated tooling to create net attachment features on said rigid body frame with respect to said new net locating scheme so that components may be attached to said automotive body at a net location eliminating the need for any slip plane attachment techniques.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part application whichclaims the benefit of copending nonprovisional U.S. patent applicationSer. No. 10/146,780 filed May 16, 2002, which claims the benefit of U.S.provisional patent application Serial No. 60/291,522 filed May 16, 2001.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

[0003] Not applicable.

BACKGROUND OF THE INVENTION

[0004] 1. Field of the Invention

[0005] The present invention generally relates to a method and apparatusfor the assembly of body components to an automotive body that hasundergone a progressive series of positioning and welding steps so as toproduce a structurally rigid body frame, termed a body-in-white. Morespecifically, this invention relates to reestablishing a new grid system(XYZ coordinate system) for a body-in-white, after assembly, so as todirect the associated tooling to establish net attachment positions forall body components thereby eliminating the B′_(L), B′_(R), C′_(L),C′_(R) need for any slip plane adjustment techniques.

[0006] 2. Description of the Related Art

[0007] For many decades, automobile and truck body frames, thattypically include at least an underbody, a pair of side frames, andfront and rear headers, conventionally undergo a progressive series ofpositioning and welding steps before a structurally rigid body frame,termed a body-in-white, is produced. Though bodies are still manuallyassembled and welded, emphasis on automated assembly and weldingoperations has for many years generated numerous automated andsemi-automated framing systems.

[0008] In an attempt to create and maintain dimensional integrity in thebuilding of automotive bodies, typically, framing systems that involve adegree of automation include the operations of locating the componentsrelative to each other on the underbody. Primary locating pointsestablished on the underbody are used throughout the body shop operationas well as in the body inspection room and are generally established bylocating on each of the rails, a four way locating pin forward and a twoway locating pin rearward. Usually, the underbody is then clamped inplace at specific points of location. The primary locating points arealso used to locate for purposes of inspection in the body build shop.The components are located relative to each other and relative to theunderbody and are loosely assembled to each other. Typically, thevarious components include a floor panel, right and left body sidepanels, a dash panel and either a roof panel or transversely extendingheader members upon which a roof panel is subsequently mounted. Afterthese individual panels are stamped, in some applications, preliminaryassembly operations are performed on individual panels as, for example,adding door hinge and latch hardware to the body side panels atapproximate locations on a door opening, adding seat mounting bracketsand reinforcements to the floor panel, etc.

[0009] The set of panels that constitute a subassembly of the finishedvehicle body are then brought together and loosely assembled to eachother. This initial loose assembly frequently is accomplished by a socalled “toy tab” arrangement in which one panel is created with a tabprojecting from one edge that is received in a slot in an adjacentpanel. This technique interlocks the panels and frame members to eachother to the point where they will not separate from each other, butdoes not achieve a rigid assembly, that is, for example, the side panelsmay tilt slightly relative to the floor panel. Alternatively, someinitial pre-tack welding may be performed in order to loosely maintainthe components together. The loosely assembled subassembly is thentransported to a framing/welding station whereat, in order to accuratelyestablish the desired final geometry of all of the components of thebody-in-white, the toy tab components are clamped to locating frames,often termed gate fixtures. Thereafter, welding operations, areperformed within a framing and subsequent respot station to morepermanently and securely weld the components together and to accuratelyform a rigid structure referred to as the body-in-white. Current bodyframing stations employ both fixed and robotic welders that can beprogrammed to perform several welds at different locations on the bodyin one framing station. The welders typically are located at oppositesides of the conveying line at the welding station, and when the body'ssubassembly is located in the welding station, the fixed weldings androbotic welders perform welds on designated areas on the body. In thosecases where clamping frames are positioned on opposite sides of thebody, clearance problems may restrict motion of the welding heads thatmust pass through the clamping frame before they have access to specificareas of the body to be welded. This will result in the performance ofonly a portion of the required welding at one station and theadvancement of the partially welded subassembly to a subsequent respotwelding station where different clamping frames allow the welding headto access those portions of the body assembly that could not be reachedby the welding heads in the first station. After the body is transportedto the final welding, or respot station the remaining welds are made toestablish a structurally rigid body frame.

[0010] Although many variations of the above process are known, it isthe general object of each framing system to accurately net locate thebody components relative to each other and maintain the established netlocation or position throughout the later welding operations, until thestructural rigidity of the body-in-white is sufficient to preserve thedesired geometric configuration throughout the assembly process.

[0011] It is readily recognized that these conventional assemblytechniques include many assembly steps that require parts to bephysically stacked on top of one another and then secured to each otherby welding, and wherein each component is created with a certainaccuracy and tolerance limits. That is, a particular component, and anypoint on that component, is typically required to be manufactured to aspecific dimensional configuration, within a specified tolerance range.If an individual panel to be affixed references a point on anotherpanel, the reference point also has a dimensional tolerance variation.The tolerance of the assembly formed by these components will also be“stacked” together. That is, the dimensional tolerance of the firstpanel will be added, to some degree, to that of the second panel to beattached thereto. As more components are fixed to the assembly thatreferences additional attachment points, the tolerances of theindividual points are “stacked” to create a greater tolerance variationfor the “stacked” components.

[0012] The small tolerance variations in the primary locating points forlocating the underbody combined with the gate fixtures that typicallyallow some play in the positioning of the panels prior to clampinginherently results in some built-up inaccuracies for the body-in-white.Also, the repositioning of the framing system in a respot station,again, results in an additional positional tolerance variationinherently creating additional inaccuracies for the location of thevarious panels with respect to each other. Accordingly, it is quiteevident that as a number of panels with positional dimensionaltolerances are stacked the total manufacturing tolerance of the framedbody-in-white will increase. Experience has shown that the “stacking”built in tolerances in the framing process increases the totalmanufacturing tolerance and can become quite substantial.

[0013] Accordingly, over a period of years, many have attempted toimprove the manufacturing method so as to reduce the overall or totaltolerance in vehicle assemblies utilizing a variety of techniques in anattempt to reduce the inherent inaccuracies of the vehicle body assemblyas well as the body-in-white.

[0014] To attempt to reduce the inherent built in inaccuracies in theprocess of building automobile bodies with the objective of reducingoverall tolerance variations, many alternative framing schemes have beenproposed over the years. For example, DeRees, U.S. Pat. No. 5,090,105,teaches a modular vehicle construction assembly method in which variousstructural modules are fabricated and assembled with operating vehiclecomponents prior to mounting with other fabricated and assembledmodules. For example, a first module having a chassis frame and apassenger platform that is used in the formation of the underbody of thevehicle is proposed. A second module in the form of a cowl or dashboardincludes a structural frame, preferably formed from stamped panelcomponents, that include a windshield frame portion integrally formedwith a dash panel frame portion. A third modular component includes aflooring platform, two first side-wall structures and at least oneclosure device extending across the first sidewall structures above orat one end of the flooring system. The fourth module includes two secondsidewall structures, reinforcement for supporting the second sidewallstructures in a fixed position with respect to each other, a hood paneland device for displaceably mounting at least a portion of the fourthmodule to the first module. Each of the first through fourth modules iscompletely assembled, including the installation of vehicle operatingcomponents, prior to its attachment to the other modules. The resultingstructure incorporates each of the modules by locating each module at anet position thereby reducing the overall built up tolerance for thecomplete assembly. However, within each module, DeReese is stillproposing that the device for securing the panels together utilizesconventional welding techniques or welding substitutes such asmechanical interlocking of the panels, mechanical fastening, bondingwith adhesives, bolting, riveting or the like.

[0015] Angel, U.S. Pat. No. 5,491,058, teaches a framing device forassembling and welding a body-in-white utilizing completely separateframing and welding operations that are typically intermixed inconventional framing systems. The framing device is a unitary framestructure within which an underbody, side frames, and other bodycomponents can each be supported and accurately positioned with respectto each other prior to the welding operation. Using an appropriatenumber of clamping devices, the net position of the body components thatconstitute the body-in-white are properly established and maintained,such that gate fixtures are unnecessary during the welding operation.The structure of the framing device provides considerable access to thebody-in-white supported within the interior of the framing device suchthat a greater number of welding guns can be used during the weldingprocess to complete all of the welding necessary to maintain therigidity and geometry of the body-in-white in a single welding operationor station.

[0016] Bonnet et al., U.S. Pat. No. 5,845,387, teach a method ofconstructing a vehicle body with reference to a single assembly stationby moving multiple panels into an assembled position nonclampingly fixedwith an adhesive and in spaced relationship without direct contacttherebetween. The vehicle body is constructed by presenting a pluralityof discrete body panels into assembled positions with respect to asingle base for application of an adhesive thereon to fix the bodypanels in a nonclamping, spaced relationship without direct contacttherebetween. The body panels include an underbody, a first side panelon a first side of the underbody and a second side panel on a secondside of the underbody, a front end member mated with the underbody, thefirst side panel and the second side panel, and a roof panelsubstantially co-planar with the underbody in mating relationship withupper mating flanges on the first and second side panels. Such structureavoids tolerance stack up between the assembled panels by controllingthe adhesive bond gap variance between the panels. The adhesive is aheavy-duty urethane structural adhesive. The resulting vehicle bodyassembly reduces tolerance stack-up and has the additional advantage ofhaving relatively little inherent stress points developed between matingpanels since they are assembled at a single stage framing fixture, orassembly apparatus.

[0017] Oatridge et al., U.S. Pat. No. 6,360,421, like DeReese, teach amanufacturing or assembly technique wherein the assembly includes aplurality of individual components that are independently formed into asubstantially rigid initial subassembly structure thereafter, for eachremaining component referencing from the substantially rigid structure adesired position for each remaining component and fixing such remainingcomponent to the subassembly at the desired position whereby the overalltolerance of the manufactured assembly is reduced.

[0018] Although a majority of the prior art has recognized the existenceof built in inaccuracies in the building of automotive bodies, by thestacking of tolerances between adjacent components, resulting inunacceptable mating conditions, little has been said in the prior artregarding those inherent inaccuracies of the various processesthemselves. For example, many of the processing techniques require therigid clamping of the various components, panels or subassemblies on thefixtures for the purpose of obtaining maximum support rigidity beforethe components are welded together. However, if any misalignment existsbetween associated components or panels, the spot welding that createsthe weld will tend to displace the component or panel from the desiredassembly location to some unknown position relative to design-intent oran established X, Y and Z Cartesian coordinate systems. Accordingly,although modular construction may be suggested to avoid tolerance buildup, the clamping of the modular components into the rigid fixtures caneasily result in stretching or compression points in the vehicle bodythat may cause stress induced cracks or other deficiencies especiallyafter the weld is created. Thus, the problem with existing fixtureswhether they are framing fixtures or tooling to assemble modularcomponents is that these assemblies are assembled with internal stressesthat can cause deformities in the assembled sheet metal resulting infailures to the assemblies when in use i.e. popped welds etc. Further,after clamping these components or panels into the rigid fixtures,thousands of welds are produced resulting in additional stresses as wellas distortion due to the heat and pressure associated with the use ofwelding guns leading to the conclusion that after the body-in-white hasbeen processed in the appropriate framing and welding stations, it isimpossible to know the final location of the surfaces as well as anytargets, master holes or whatever else is attached to the panels beforethe welding operations occur. Although the objective in the framing andwelding station is to locate panels at so called “net” or design-intentlocations, the variety of unknowns due to processing through thestations causes every vehicle body and its associated surfaces to bebuilt differently. In the past this has been considered to be anacceptable body to process providing that master attachment points orpanels are within an acceptable tolerance range from net ordesign-intent location. For decades, it has been common practice in theautomobile industry to incorporate a “slip plane” in the assembly ofouter body panels to the body-in-white. The slip plane enables theappropriate outer panels to be attached and manually fit at assemblyrelative to adjacent panels. Until recently, a slip plane was necessaryin order to meet quality and fit requirements of the marketplace andcompetition, and to provide an appearance that is more pleasing and moreaerodynamic due to flushness and/or alignment of features on an outerpanel with adjacent outer surfaces of a vehicle.

[0019] Slip planes are designed in component assemblies where as aresult of manufacturing variations of the components, as for example adoor and a hinge on a vehicle, it is necessary to provide a device toenable a door to be manually fit to the body opening at final assembly.The slip plane permits fore/aft and up/down adjustment of the hinge asnecessary to permit the door to be fitted within the body opening withan equidistance gap around the door and between body openings. Slipplanes can be planned to be within any coordinate or plane of an X, Yand Z coordinate system as for example on a vehicle the fore/aftdirection, cross-car direction and up/down direction that arerespectively designated as X, Y and Z. The appropriate plane toincorporate a slip plane is based on the specific surface featurerequired to be aligned with respect to an adjacent surface feature on anadjacent outer panel of the vehicle body. The slip plane is anadjustment feature that compensates for the inevitable tolerancevariations that differs between vehicles. Slip planes are generally usedat the interface between attachment points as for example a door hingeand the major trim panels to which the hinge is to be attached to thevehicle body. Because of the tolerance variations of the body-in-white,excessive gapping may result between panel or between the door and adoor opening. Further, in the case of moving trim panels such as doors,and decklids, pinch points may occur as a result of variation inlocation of the attachment point with respect to the opening in whichthe major panel is mounted. Accordingly, a slip plane, as for example inthe door hinge and/or door panel, has always been used to provide formanual final fitting of the door with respect to the door opening tobalance out the gap between the doors and major trim panels, such asfenders, as well as to ensure proper flushness of adjacent major outerpanels.

[0020] The problem of inherent stresses and distortions as a result ofthe assembly process has been recognized in the prior art and severalattempts to provide more accuracy in the assembly process of a vehiclehave been made in order to solve the problem.

[0021] Earlier, it was believed that by establishing the attachmentpoints at net or design-intent position on the body-in-white framestructure at least some of the inaccuracies between the panel to beattached and the body-in-white would be eliminated. However, due to thedistortions of the body-in-white as a result of the assembly/weldingprocesses, it was still necessary to provide a slip plane in order topermanently attach the outer body attachment panels for the purpose ofobtaining proper gaps and correct flushness between adjacent panels aswell as alignment of feature lines between adjacent panels. Theapparatus and process by which a device established a datum positionfrom an object having dimensional variations within a known tolerancerange is disclosed in U.S. Pat. No. 4,976,026 to Dacey, Jr. and is ownedby the current assignee hereof. Dacey Jr. teaches an apparatus andmethod for establishing a location in space (a datum position) utilizingan object having dimensional variations in each of the X, Y and Z planeswithin a known tolerance range. Upon establishing a location in space,the device is immobilized at the datum position and work is performed onthe body-in-white with respect to the datum position. The apparatusincludes a fixed base structure for rigid mounting to a floor adjacentto an assembly line, a transfer platform moveably attached to the basestructure so that the transfer platform can move in a horizontaldirection with respect to the fixed base structure, a support structureassembly attached to the transfer platform that is adapted to move in ahorizontal direction perpendicular to the direction of movement of thetransfer platform, a vertical slide assembly moveably attached to thesupport structure assembly and moveable therewith in a verticaldirection, fluid actuated positioning and locating members attached tothe apparatus for immobilizing the horizontal and vertical movements ofthe apparatus, as well as a plurality of probes attached to theapparatus for locating pre established selected reference surfaces orgage points from which the datum position can be established. Theinvention further includes a work performing tool attached to theposition finding apparatus so that it can perform work on the objectwith respect to the established datum position. Since the apparatus ofDacey Jr. relied on utilizing reference positions on the body-in-white,that resulted from imprecise and unknown locations due to the inherentstresses and distortions created during the assembly process, thepositions were continuously different although within an acceptabletolerance range on each body-in-white. The datum position establishedbased on these unknown distortions of the body-in-white created by theassembly and welding processes provided so called “design-intent”positions that varied significantly as a function of the inaccuracies ofthe vehicle frame created during assembly.

[0022] Akeel, U.S. Pat. No. 5,987,726, teaches a solution to avoid thecreation of internal stresses that could cause failure of the assemblieswhen in use. Akeel, teaches an apparatus for positioning an objectduring an assembly operation including a parallel link programmablepositioning mechanism having a base plate, a spaced apart locator plateand six linear actuator links extending between the two plates andattached thereto by universal joints. The base plate is connected to thelocator plate with the plurality of linear actuators, each having alower end pivotably attached to the base plate and an upper endpivotably attached to the locator plate. When an object is mounted onthe locator plate, the linear actuators are controlled to move thelocator plate to a predetermined position relative to the base plate forcontacting the object mounted on the locator plate with a component tobe assembled. A feedback signal is generated representing a forcesupplied to the locator plate when the object contacts the component andthereafter the linear actuators are actuated to change the applied forcein response to the feedback signal. This locating method provides for astress free assembly of sheet metal components on assembly fixtures.

[0023] Kotake et al., U.S. Pat. No. 5,150,506, also teach a method ofassembling exterior parts of an automobile wherein assembly accuracyerrors of the vehicle body or body-in-white are determined by measuringthe actual positions of a plurality of reference points of thebody-in-white after it has been processed through the framing/weldingstation. Correction data is then generated by comparing the actualmeasured position of a point to the wire frame data or design-intentposition of the same point while maintaining a correlated relationshipamongst the parts, to eliminate correlated misalignment among thoseparts due to assembly accuracy errors of the body. The measurement ofthe assembled position of the vehicle body may be made at the assemblystation of the parts or at any arbitrary station that is located on anupstream side of the assembly station. In the latter case, the measuredas assembled, data is read by a processor that generates correction datafor the parts assembled positions that is transmitted from the measuringstation to the assembling station. When the vehicle body is conveyedinto the assembling station, the conveyed position is detected byencoders and the parts are assembled after corrections are made inaccordance with the correction data. The reference points of the vehiclebody are detected by the encoder device provided at the assemblingstation and, on the basis of the positional information, correction datafor each assembling position of an exterior part is calculated bycomparing the actual position detected by the encoders with the wireframe data in a computer so that the correction data is transmitted to arobot controller of a corresponding assembly robot to correct theassembling position of each part.

[0024] Accordingly, as desired, the location of any individual point ona panel after the body has been welded together is determined by the useof encoders and the deviation from the mean position of the point iscalculated by comparing the actual reading to the net location of wherethat point should be so that a deviation from mean of the location ofthe point is determined. This deviation, in the form of a correctiondata, is communicated to the assembling robot in order to instruct therobot of the actual position of the point on the body-in-white panelwith respect to the design-intent position so that each component to beassembled at that point may be separately adjusted to a correctedposition in order to provide a corrected attachment point for assemblingeach of the outer body panels to the appropriate holes formed in theunderbody and thereby maintain flushness of adjacent panels.Accordingly, each attachment point is selectively investigated as todeviation from mean and a correction is made when comparing the actuallocation of the attachment point to the mean location to ensure that theholes in the outer panels line up properly with the holes in theunderbody to enable a successful attachment of the outer panel andensure flushness to adjacent panels. Obviously, when using thissophisticated equipment in a production environment many problems cansurface including but not limited to, environmental debris as a resultof welding operations, sensitivity problems with the equipment technicalsupport team necessary to monitor equipment, etc. Also an additionalstation is needed in the production line to enable measurement by theencoders of the actual points on the body-in-white.

[0025] Therefore, what is needed is an apparatus and technique forassembling automotive frame components that recognizes and accepts theexistence of these internal stresses and distortions of the variouspanels constituting the body-in-white that have been welded with, insome cases, as many as three thousand welds, yet is able to establish areliable assembly technique utilizing a feature of Dacey Jr., that is,insuring the fabrication of attachment points that are in a net or bestfit position on the complete body-in-white that is also then assured tobe in a known position so that the outer panels may be directly attachedto the body-in-white with attachment points assured to be in the sameposition so that the outer panels may be directly attached to thebody-in-white without the need for slip planes and without the need forbeing concerned of the inherent variations established by the bodybuilding process itself.

BRIEF SUMMARY OF THE INVENTION

[0026] According to the present invention, there is provided a methodand apparatus for optically establishing a new master locating schemefor an automotive vehicle body, otherwise known as a body-in-white, andthereafter using robotically driven tools precisely assemble componentsto the body-in-white relative to its new master locating scheme. Afterthe body-in-white has been processed through the framing/weldingstation, s work performing tools is robotically positioned with respectto the new master locating scheme and work is performed on thebody-in-white to create net or best-fit attachment features adapted toaccommodate the attachment of other components and thereby produce afinished vehicle body that meets the flushness and gap specificationsbetween adjacent panels established by the vehicle design team.

[0027] The apparatus of the present invention is intended to be part ofthe production assembly line after the various panels have been framedand welded together as a unit to establish a completed body-in-white.The body-in-white is transported by a carrier device along the assemblyline, and is provided with a predetermined arrangement of datumstypically including reference holes, slots and/or surfaces. Theapparatus includes two and three-dimensional optical sensors, such asthose commercially available from Perceptron, Inc., positioned on eachside of the assembly line relative to a predetermined datum feature ofthe body-in-white. Each optical sensor is adapted for locating up/down,fore/aft and cross-car datum features of the body-in-white, and forcommunicating such location to a microprocessor. As the optical sensorslocate features that have surfaces which have been processed through theframing/welding station. The effect of distortion of these features onsurfaces and other inherent process variables of the body-in-white as aresult of the assembly and welding processes, will be realized by thesesensors.

[0028] The microprocessor establishes specific points in terms of theCartesian X, Y and Z coordinate system that represent the primarylocating points of the body-in-white as built, that is, including theinherent tolerance variations and distortions caused by the framing andwelding operations. The microprocessor then compares the primarylocating points of the body-in-white as built with the design-intentprimary locating points and divides the total variable in half togenerate new X, Y and Z centerlines that takes into account thevariations and distortion of the body-in-white in the as built conditionas will be discussed in more detail hereinafter. The present inventionis adapted to create separate X, Y and Z centerlines or gridlines forthe body-in-white attachment locations as required for a particularapplication. For example, the optical sensors may be configured tolocate a first group of reference datums near the front of thebody-in-white to create a first specific set of X, Y and Z coordinatecenterlines for the attachment of the hood, and a second group ofreference datums near the rear of the body-in-white to create a secondspecific set of X, Y and Z coordinate centerlines for the attachment ofthe trunk.

[0029] The new X, Y and Z coordinate centerlines of the body-in-white asbuilt are then communicated to the robotically positioned workperforming tools that perform work relative thereto. As a result ofbeing able to balance out any created or inherent errors of thebody-in-white due to processing through the framing station, allattachment holes, slots, pads etc. created by the work performing toolscan be located with respect to the newly established X, Y and Zcoordinate system and therefore all locations of the attachment featuresare net to the newly created X, Y and Z coordinate system. Furthermore,the new mastering scheme creates the absolute best-fit attachmentfeature and completely eliminates the need to provide for a slip planein order to attach a component to the body-in-white. Therefore any outerbody component, i.e. hood, fender, doors, decklid, liftgate, frontbumper, rear or front fascia etc. being attached to the body-in-whitecan be fabricated with attachment feature at net or design-intentpositions since they will be attached to a net attachment point on thebody-in-white.

[0030] The invention also encompasses a method for establishing a newCartesian X, Y and Z coordinate system taking into account the inherenterror created by assembling the various panels of a vehicle body in aframing and/or welding station.

[0031] The method of establishing a new coordinate system taking intoaccount the variations of the as built vehicle body upon which work isto be performed is set forth. The method also encompasses theperformance of work on the vehicle body at a location remote from aplurality of independently established primary locating points.

[0032] The principle object of the present invention is to provide a newand improved apparatus and method for establishing a new Cartesian X, Yand Z coordinate system for a vehicle body otherwise known as abody-in-white. The invention encompasses performing work at this new X,Y Z coordinate or grid system so as to provide net reference attachmentfeatures for the various components that will subsequently be attachedto the body-in-white.

[0033] Another object of the present invention is to provide a new andimproved apparatus and method of balancing out the inherent errorgenerated by the processing of the body-in-white through the framing andwelding operations.

[0034] A further object of the present invention is to perform work on abody-in-white relative to a newly established X, Y Z coordinate systemso as to provide new net attachment features for the various outer bodypanels and/or attachments to be made to the body-in-white.

[0035] Still another object of the present invention is to provide anapparatus that can interact with a body-in-white and generate a newreference position with respect to known design-intent referencepositions, balance out any errors at this given reference position andestablish a new reference coordinate system for the body-in-white sothat, thereafter, work can be performed on the vehicle body at alocation remote from the established reference position.

[0036] Another object of the present invention is to provide anapparatus that relies primarily on a programmable robotic device andassociated microprocessor system for accomplishing part of its motionrelative to an adjacent workpiece.

[0037] Also, another object of the present invention is to provide anapparatus that has freedom of movement in at least three dimensions tolocate and lock on primary locating points of unknown dimensions andthereafter reestablish a new net X, Y and Z coordinate system for theprimary locating points that are used, in turn, by the associatedtooling to perform work relative to the new net X, Y, Z coordinates onthe vehicle body to create attachment features for outer panelcomponents thereafter intended to be attached to the body-in-white.

[0038] Another object of the present invention is to provide a methodfor the manufacturer of attachment features on a vehicle body-in-whitestructure that are created with reference to a newly established X, Yand Z coordinate system based on balancing out the inherent errorsexisting in the body-in-white from the framing and welding operations.

[0039] Yet another object of the present invention is to provide aprogrammable apparatus that has attached thereto a work performing toolnet located to a newly established X, Y and Z coordinate system for theobject whereafter the tool is located and held by the programmableapparatus for a time interval sufficient to permit the tool toaccomplish its task and be withdrawn from the proximity of the objectbeing worked on.

[0040] Yet another object of the present invention is to establishattachment references on a body-in-white without the use of slip planes.

[0041] Still a further object of the present invention is to provide aprogrammable apparatus for reforming an element of an automotive innerbody panel to present a portion of the surface of such element at apredetermined net position with respect to a newly generated X, Y and Zcoordinate system for the attachment of an outer body panel thereto.

[0042] It is a further object of the present invention is to provide aprogrammable apparatus and method for establishing a new X, Y and Zcoordinate system of an automotive inner body panel to present a portionof the surface of such element at a predetermined position for theattachment of another element thereto by a robot and for forming a nethole in such surface to facilitate the attachment of the elementthereto.

[0043] For a further understanding of the present invention and theobjects thereof, attention is directed to the drawings and the followingbrief descriptions thereof, to the description of the preferredembodiment of the invention and to the claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0044]FIG. 1 is a top view of a partial body-in-white located in thepreferred embodiment master locating station with a gantry and whereinthe tooling has been removed in order to clearly view the positiondetecting apparatuses, the front two of which are engaged with thevehicle body;

[0045]FIG. 2 is a partial isometric view of the position detectingapparatus located in the front right hand primary locating points of thevehicle shown in circle 2 of FIG. 3;

[0046]FIG. 3 is an isometric view of the master locating station withthe right side position detecting apparatuses located on the right sideprimary locating points and the left hand position detecting apparatusesand all associated tooling removed;

[0047]FIG. 4 is a schematic representation of the top view of the frontprimary locating points misaligned from design-intent due to theinfluences of the work performed on the body-in-white in theframing/welding station;

[0048]FIG. 5 is a schematic representation of a misalignment of thefront primary locating points as viewed from the rear of the vehiclebody so as to show the misalignment in the up/down direction of theprimary locating points;

[0049]FIG. 6 is a top view of the master locating station with a portionof the front gantry cut away to better illustrate the attachment of thebalancing lever and crank mechanism to the underside of the gantryspanning the production line;

[0050]FIG. 7 is a partial view of the gantry spanning the productionline, having the level and bell crank system attached to the bearing andslide mechanism that is secured to the underside of the gantry;

[0051]FIG. 8 is a front end view of the master locating station with theright side front position detecting apparatus, probes, and contact blocklocked in place and the associated locator pin inserted in the overheadsocket to establish the location of a new X, Y, and Z coordinates forthe primary locating points of the vehicle body;

[0052]FIG. 9 is a detailed view of only the input socket arrangementattached to the end of a lever of the bell crank system with the locatorpin in the bottomed-out position as shown in circle X of FIG. 8;

[0053]FIG. 10 is a partial view of the master locating stationhighlighting the lever and bell crank centering arrangement, having aninput and output socket attached thereto with the respective locator pinaligned with a first position detecting apparatus and additional locatorpin aligned with a second position-detecting apparatus;

[0054]FIG. 11 is a detailed view in the fore/aft direction from thefront of the vehicle body of both input and output sockets with locatorpins bottomed-out as shown in circle 11 of FIG. 8;

[0055]FIG. 12 is a partial view in the cross-car direction of thebearing and slide mechanism and associated input socket attached to aposition detection apparatus and output socket attached to anotherposition detecting apparatus directly attached to the tools, whichperform work on the vehicle body;

[0056]FIG. 13 is a top view of a partial body-in-white located in aworkstation showing electro-optical position detecting apparatuses,which are engaging with the vehicle body;

[0057]FIG. 14 is a block diagram of associated electronics of theworkstation of FIG. 13;

[0058]FIG. 15 is a schematic representation of the top view of theprimary locating points misaligned from design-intent due to theinfluences of the work performed on the body-in-white in aframing/welding station and the new grid established as a result ofaveraging out the total deviation from design-intent of the actuallocation of the primary as built locating points; and

[0059]FIG. 16 is a schematic representation of a misalignment of theprimary locating points as viewed from the front of the vehicle body soas to show the misalignment in the up/down direction of the primarylocating points and the establishment of a new grid centerline atone-half the total deviation of the as built location as compared todesign-intent location.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0060] Generally shown in the Figures, is a method and apparatus forutilizing position detection apparatuses to locate primary locatingpoints on a vehicle body, also known as a body-in-white. In accordancewith the present invention, after the primary locating points have beenlocated and the position detecting apparatus have been locked in place,a set of locator pins and input sockets, one of which is attached to theposition detecting apparatus and the other of which is attached to abalancing lever mechanism fixed to the gantry spanning the productionline, is used to balance out or average the deviation of the primarylocating points in cross-car, fore/aft and up/down directions of theactual body-in-white as built, from design-intent positions. Thisaverage or balancing out would obviously not be required if theprocessing of the body-in-white resulted in all panels and attachmentpoints being actually located at design-intent position after thevehicle body was processed through the framing and welding station.Unfortunately, a perfect body-in-white exists only in sophisticated CADsystems on a computer. In the real world, bodies-in-white are made witha variety of assembled parts, each having tolerance variations resultingin tolerance stack-ups. Further, the effect of as many as three thousand(3000) welds make it impossible to predict the final assembled locationof any point on the body-in-white with any great specificity.Accordingly, tolerance variations of any point on the body-in-whiteafter processing are expected, and acceptable within a given tolerancerange. The invention contemplates balancing out these unknown variationsand therefrom create a new known X, Y and Z coordinate system or gridfor the body-in-white in the “as built” condition. A second set ofoutput sockets and locator pins, one of which is mounted to thebalancing mechanism, the other being mounted to a second positiondetecting apparatus associated with the tooling surrounding thebody-in-white, interact or plug into each other to float the toolingstation into a net position with respect to the newly created coordinatesystem, created by the balancing technique, so that work may beperformed on the body-in-white relative to a new net X, Y, Z coordinatesystem of the body-in-white.

[0061] In the context of the following detailed description of thepreferred embodiment, which is a vehicle body for an automobile,reference to the fore/aft (X), cross/car (Y), and up/down (Z) axis, aswell as the relative terms front, rear, top and bottom, apply to avehicle body as viewed in the final assembled position unless otherwisespecified. Also, reference to a “Class A” surface means any surface onthe completely assembled automotive vehicle body that is visible to anobserver.

[0062] With reference now in detail to the Figures, FIG. 1 shows aportion of a body-in-white A in a master locating station 10 having afront gantry 12 and rear gantry (not shown) with appropriate positiondetecting apparatuses 20 located selectively at four feature points orprimary locating points (not shown) on the body-in-white A so as to findthe actual location of unknown primary locating points on thebody-in-white and thereafter immobilize the position detectingapparatuses 20 with respect to the primary locating points of thebody-in-white A. It is understood that the primary locating pointsselected can change based on the requirements of the specific vehicle aswell as what subjectively may be determined by the body building team tobe important features that need to be properly fit for gapping orflushness, or relative importance, as a feature line across the completebody side of the vehicle body.

[0063] The position detecting apparatus selected 20 is described indetail in Dacey Jr., U.S. Pat. No. 4,813,125 owned by the assigneehereof and that is incorporated herein by reference in its entirety. Forthe purpose of clearly understanding the current invention, some limiteddescription of the position detecting apparatus 20 is provided. Theapparatus as described in U.S. Pat. No. 4,813,125 includes a fixed basestructure for rigid mounting to a floor adjacent to an assembly line, atransfer platform is movably attached to the base structure so that thetransfer platform can move in a horizontal direction with respect to thefixed base structure. A support structure assembly in the form of anangle plate is mounted to the transfer platform that in turn is adaptedto move in a horizontal direction perpendicular to the direction ofmovement of the transfer platform. A vertical slide assembly is movablymounted to the angle plate of the support structure and movable withrespect thereto in a vertical direction. Fluid actuated positioning andlocating members are attached to the apparatus to permit limitedmovement with respect to all three directions, that is X, Y and Zdirections and further includes a device for immobilizing the horizontaland vertical movements of the apparatus. A plurality of probes and/orcontact blocks are attached to the position detecting apparatus forlocating selected pre-established reference surfaces or primary locatingpoints on the vehicle body so that the position detecting apparatus canmove into position at the primary locating points in order to “find” thelocation of these points in an X, Y and Z coordinate system within aknown tolerance range. Although the position detecting apparatus 20selected is a mechanical device, it is within the scope of the inventionthat vision systems, electro-optical or other suitable sensors, orlasers in combination with robotic tools may be used to detect theposition of selected primary locating points on a body-in-white.

[0064] As shown in FIG. 1, the position detecting apparatuses 20 arelocated on each side of an assembly line spaced with respect to thebody-in-white A that will be processed therethrough. For purposes ofclarity the rear gantry spanning across the production line and all ofthe associated tooling are not shown and further, the completebody-in-white A is not shown so as to enable viewing the positiondetecting apparatuses 20 in the front and the rear of the masterlocating station 10. FIG. 2 is a close up of the right front quarter ofthe vehicle body A being processes wherein the position detectingapparatus 20 has been isolated and illustrates a probe 22 located in agage hole in the front pillar, defining a primary locating point B, toestablish X and Z positions as well as a contact block 24 touching thevehicle in order to establish a cross-car or Y position of a Class Asurface C on the front pillar.

[0065] The contact block 24 is adapted to carry a low DC voltage so asto electrically sense contact with the pillar surface to avoid creatingan external force on the vehicle body A that could influence theposition or location of the Class A surface. The position detectingapparatus 20 moves into position against the body-in-white A toestablish a cross-car location by touching the contact block, and afore/aft X and up/down Z location by locating in the gage hole B. Aftereach of the position detecting apparatuses 20 as shown in FIG. 1 havemoved into place by finding their respective primary locating point onthe vehicle, the position detecting apparatuses 20 are immobilizedaccording to the teachings of Dacey Jr. To a person skilled in the artit should be obvious that in order to establish the immobilized positionof all four position detecting apparatuses 20, the vehicle body A mustcome to a complete stop position in the master locating station 10. Thebody-in-white A enters the master locating station 10 located on thesame primary locating points as established in the framing system. Theseprimary locating points are the same points used to locate the bodythroughout the body shop operations as well as in the body inspectionroom and generally includes locating on each of the rails, a four waylocating pin forward and a two way locating pin rearward. Thebody-in-white A is then clamped in place and remains at the clampedposition throughout the master locating stop station and subsequentassembly stations.

[0066] For the purpose of clarity, and with reference to FIG. 3, thereis shown a master locating station 10 with the appropriate gantries inthe front 12 and rear 14 of the vehicle body that straddle theproduction line as well as the position detecting apparatuses 20 used tolocate on the right hand side of the vehicle. The remaining positiondetecting apparatuses are not shown for the purpose of clarity. Howeverit is understood that the following discussion of the operationconcerning the right front quarter position detecting apparatus 20equally applies to each of the position detecting apparatus 20 in thecreation of a new X, Y and Z coordinate or grid system based on thevehicle as built with the aforementioned variations, distortions andinherent processing errors. The work performing tools are also not shownin FIG. 3.

[0067]FIG. 3 represents a master locating station 10 that includes agantry 12 at the front of the body wherefrom is suspended a lever andcrank centering mechanism 30 that can move fore/aft (X) and cross-car(Y) on a slide assembly 50 utilizing a plurality of bearings and ways inorder to be moved in the fore/aft and cross-car directions for a purposehereinafter described. As shown in FIGS. 2 and 3, the position detectingapparatus 20 has been moved in place by the insertion of the probe 22into a primary locating point or gage hole B in the body pillar as wellas by a contact block 24 creating contact with the vehicle Class Asurface C so as to find and locate the exact position of the selectedprimary locating point for the front quarter panel of the vehicle body.The position detecting apparatus 20 has been immobilized and is lockedin this position. Since all position detecting apparatuses 20 operatesimultaneously in order to establish the location of all of the primarylocating points on a vehicle body, once immobilized, all fourapparatuses 20 are now positioned with respect to selected primarylocating features on the processed body-in-white A. As recognized by anyperson skilled in the art, the primary locating points will vary betweenvehicle platforms and due to the distortions and stack up tolerancescreated in the framing and welding station, the position of the Class Asurfaces will also vary from body assembly to body assembly and evenfrom side to side of the same vehicle body, as will be illustratedhereinafter.

[0068] For the purpose of illustrating the invention, and with referenceto FIG. 4, once the position detecting apparatuses 20 are immobilized,the representation conceptually in FIG. 4, as viewed from the top of thevehicle body A, reflects the position of the right hand positiondetecting apparatus 20 as shown in FIG. 3 located at the primarylocating point B, C in a direction fore/aft further rearward from theposition detecting apparatus 20 located on the left hand side of thevehicle body A. From this, it can easily be concluded that thebody-in-white A, as a result of distortions by processing through theframing station has moved. As a result the gage hole B and associatedcross-car centerline B-B C between the two primary locating points B, Bhas moved rearward from the cross-car design-intent centerline D whilethe gage hole B and associated centerline B-B C on the left hand sidehas moved forward from the design-intent position D. Also, in thecross-car direction, the contact blocks from left to right hand sidehave detected a shift in the class A surface of the pillar since theright hand side surface is further inboard from design-intent while theleft hand Class A pillar surface is further outboard from itsdesign-intent position as reflected by the cross-car design-intentcenterline D. Similarly, FIG. 5 represents a conceptual view of the twofront position detection apparatuses 20 located in the master gage holeB, as viewed from the rear of the vehicle body. The centerline B₁ C, ofthe primary locating feature B on the left hand side is substantiallylower than the centerline B₂ C, of the master gage hole B on the righthand side of the vehicle body. The obvious reason for this is the factthat the body-in-white A, as processed through the framing and weldingstation, has inherent variations and distortions in the various panelsin which these primary locating points are located and accordingly,these primary locating points are not at design-intent position D nor inany way representative of the X, Y, Z planes or grid lines about whichthe design-intent body is designed. It is clear that the body-in-whiteA, due to its processing, has somehow been skewed in the FIG. 4 and FIG.5 schematic representations. Any outer panel that references thesepoints B, B as currently depicted in FIG. 4 and FIG. 5 will naturallyrequire fit and spacing adjustments to adjacent body panels and thisclearly shows why in the past, a slip plane had to be used in order toallow adjustment of these panels because of the unknown variations ofthe primary locating points for attachments to or referencing of theouter body panels.

[0069] The invention contemplates adjusting the tooling with respect toadjusted averaged newly established X, Y and Z reference planes createdby averaging out the distance d between right B and left B primarylocating point as viewed in FIG. 4 or FIG. 5 so that the tooling canutilize this new adjusted average X, Y and Z grid positions to establisha new net reference location and perform work with respect thereto. Thenet effect of this averaging results in reducing total deviation errorfrom design-intent to one-half, as well as to establish an actual netlocation of the “as built” body-in-white A and utilize the newlyestablished X, Y and Z coordinates as a new grid system from which toreference the tooling so that new net attachment points can be providedon the body-in-white A enabling the attachment of components to thevehicle body at the new net attachment point without the need foroversized holes or a slip plane.

[0070] The new net locating X, Y, Z coordinate system is establishedthrough the use of a lever and crank mechanism 30 that is attached toeach gantry 12, 14 for respective fore/aft and cross-car finalpositioning of attachment points. With reference to FIGS. 6 and 7, thereis shown the lever and bell crank system 30 encompassing a crank arm 34located at the exact design-intent centerline D of the vehicle to beprocessed with attached sockets 40 located at the end of each 32 leverhaving one end attached to the socket and the opposite end attached tothe crank arm 34. The lever and crank system 30 is biased in theclockwise direction so that the cross-car dimension between sockets isless than the design-intent dimension, by an amount corresponding to theacceptable total deviation range so as to always insure that the socketis within range of a locating pin to be moved into it, as hereinafterdescribed.

[0071] Referring to FIG. 8, the first set of sockets 40, are mounted ona bearing and a slide assembly 50 that is movable in the fore/aftdirection 52 as well as cross-car direction 54 of the complete lever andcrank system. The position detecting apparatus 20 communicate with thebell crank system 30 through the use of a locating pin 62 and cylinder60 arrangement securely fixed to an opposite end of the positiondetecting apparatus 20. The locating pin 62 can extend from the cylinder64 in an upward direction. As the locating pin 62 extends toward andinto the socket 40, a set of rollers 74 (shown in detail in FIG. 9)mounted 90° with respect to each other form a pocket to receive a bullnose of the locating pin 62 that continues to travel within the socket40 until it bottoms out. Any effect of a misalignment between flats 64on the locating pin and the socket 40 generates a force on the lever andbell crank 30 thereby creating rotation of the bell crank and leversystem 30 and, at the same time, the rotation forces movement of theslides along the bearings of the slide assembly in the fore/aft 52 andcross-car 54 direction. Through the lever and bell crank mechanism 30, abalancing occurs between the two front sockets 40 mounted on either sideof the body-in-white A. Similar balancing occurs between the two rearsockets (not shown). The total amount of movement is a function of thetotal deviation from design-intent from which each of the primarylocating points B have been moved to as shown in FIG. 4 and 5 due to theframing/welding station processing.

[0072] As shown in FIG. 4 and 5, the adjustment will be balanced betweenright and left sides because of the socket 40 and locator pin 62interaction and by this balancing action, the bell crank and slidemechanism 50 will balance out at a new net cross-car position and ineffect create a new centerline N₁ in the fore and aft, or X direction,based on actual vehicle body built conditions. Further, a second set ofrollers (not shown) within the socket 40 also are influenced by theinteraction of the locating pin 62 to create movement of the bearing andslide system 50 in the cross-car direction to balance out at a newcross-car position and create a new cross-car centerline N₂ that is anet centerline for the actual vehicle body as built in the cross-car orY direction. A third movement of additional locator pins inserted intoassociated sockets and related movement of the slide system to which thebell crank is attached is simultaneous in both the front and rear of thevehicle body A (not shown). Accordingly, when both locating pins 62 arefully inserted into the first set of input sockets 40, a new centerlinefor the body-in-white A, in the “as built” position, is created in the Xand Y directions. A similar locating pin and socket arrangement (notshown) is provided in the up/down or Z direction of the vehicle with asimilar crank and lever mechanism to accomplish a similar balancingaffect (not shown) so that a new centerline N₃ or net locating line forthe Z direction is established as illustrated in FIG. 5. Upon completeinsertion of the locating pins 62, in their respective sockets 40, alimit switch detects the presence of the pin 62 and securely locks thepins 62 in place in the first input sockets 40.

[0073] Now that the variation of the inherent errors of the processingof the body-in-white has been balanced out or averaged across a new setof X, Y and Z centerlines, as discussed above, and the locator pins 62have bottomed out in their respective sockets 40 the work performingtools (not shown) can be brought into place to perform work on thebody-in-white. This is accomplished by providing an additional set ofsockets 70, commonly referred to as, output sockets as shown in FIGS.8-12.

[0074] Additional set of output sockets 70 are physically attached tothe same slide and bearing assembly 50 mounting plate as the first setof input sockets 40 attached to the bell crank and lever system 30. Anadditional position detecting apparatus 80, directly attached to all ofthe tools that surround the body-in-white A, is spaced relative to thefirst position detection apparatus 20. Accordingly, as the positiondetecting apparatus 80 floats to permit complete insertion of a locatorpin 72 in the output socket 70 the tooling will relocate itself withrespect to the new X, Y and Z gridlines for the body as built. Thissecond set of sockets 70 receives the locator pin 72, of additionalposition detecting apparatus 80 located adjacent the immobilizedposition detecting apparatus 20. Since the output sockets 70 are fixedto the bearing and slide structure 50 as the locator pin 72 is locatedor floated into the fixed output sockets 70 the position detectingapparatus 80 floats in all 3 directional planes to allow the pins 70 tocompletely position itself and bottom out in the sockets 70.

[0075] As the position detecting apparatus 80 floats into place thecomplete tooling system directly or indirectly attached to the secondposition detecting apparatus 80 will also float so as to position itselfnet with respect to X, Y and Z coordinates and relative to the newcenterlines N₁, N₂, N₃, based on the actual built condition of thebody-in-white A. When the locator pins 72 bottom out in the outputsockets 70, a signal is generated and communicated to the secondposition detecting apparatus 80 so as to immobilize this apparatus inthis position thereby establishing a net location for all workperforming tools relative to the new net coordinate system, that is, X,Y and Z that reflects the actual body as built wherein the totalvariations and distortions of the selected primary locating points havebeen averaged out to set a new net position from which tools can performwork on the body-in-white A.

[0076] The work to be performed on the body-in-white A and the sequencein which to perform the work can vary. Generally, a person skilled inthe art will recognize that the speed at which this work is accomplishedis a direct function of the access that is created for each of the workperforming devices. The majority of the work concerns piercing holes forattachment of outer body panels such as doors, decklid, liftgate,bumpers, facia, hood, and fenders. However, it is also contemplated thatattachment features can be established for head lamps, shock towers,tail lamps, fuel filler, instrument panel, seats, consoles and the like.All of the work performing tools operate under principles that need notbe described herein.

[0077] While the method and apparatus of the invention has beendescribed by way of illustration involving 4 position detectingapparatuses in conjunction with two lever and crank units to balance outand establish a new X, Y and Z reference coordinate system for abody-in-white, it is within the purview of the present invention toestablish and immobilize any two or more position detecting apparatusesand an associated lever and crank balancing or averaging mechanism,thus, creating a new X, Y and Z grid system or reference planes fromwhich useful work can be performed.

[0078] As stated previously above, it is within the scope of the presentinvention that the position detecting apparatus can also take the formof an optical sensor such as a laser. Accordingly, FIG. 13 illustrates aplan view of an alternative embodiment of the present invention thatrepresents an electro-optical analog to the mechanical embodimentdescribed previously with reference to FIGS. 1 through 12. Whereas, thepreviously described embodiment mechanically re-established a coordinatesystem for an as-built vehicle body, this embodiment, using amicroprocessor, electro-optically re-establishes a coordinate system foran as-built vehicle body so that work can be performed by toolingdirected by programmable robots.

[0079]FIG. 13 generally illustrates a workstation 110 for processing abody-in-white, or vehicle body A. The workstation 110 is ultimatelydirected to forming net-located attachment features programmed bycomparing as built positions with design-intent positions andestablishing a new net or best fit attachment feature on the vehiclebody A, regardless of the as built location of the vehicle body A. Inother words, the objective of the workstation 110 is to net-locate suchattachment features with respect to a newly established net grid systemrelative to design-intent vehicle body coordinates, regardless of theposition, location, or orientation of the body-in-white coordinatesafter the effects of the framing/welding operation. The presentinvention is particularly effective if the actual vehicle bodycoordinates of actual or target locating features B′_(L), B′_(R),C′_(L), C′_(R) are within tolerance. If, however, the target locatingfeatures B′_(L), B′_(R), C′_(L), C′_(R) are not within theirpredetermined tolerance band coming into the workstation, then thepresent invention is not designed to correct for such out-of-toleranceconditions and the vehicle body may need to be rejected and repaired. Asdefined herein, the terminology—target locating feature—is equivalent tothe terminology primary or actual locating feature. Also as definedherein, an attachment feature can be an attachment point, surface,position and the like. Likewise, a target locating feature can be alocating point, surface, position, and the like.

[0080] The workstation 110 is just one station of a much larger vehicleassembly line. The vehicle body A may arrive at the workstation 110 inany manner including on a sled, conveyor 112, or the like. Preferably,once the vehicle body A occupies a desired position within theworkstation 110, locator pins 114 engage preformed setup locatingfeatures (not shown) on the vehicle body such as on an underside of thevehicle body A near the four comers thereof, as is well-known in theart. Two-way and four-way locator pins (not shown) could also be used asdescribed above with respect to the mechanical embodiment. The locatorpins 114 are permitted to float to a certain extent to accommodatedimensional variations in the predefined locating points on the vehiclebody A.

[0081] The workstation 110 also includes several position detectingapparatuses 116 that are interfaced to a common machine visioncontroller 118 as shown in FIG. 14. A pair of up/down position detectingapparatuses 116 are mounted to an overhead frame 120, under which thevehicle body A is stationed. An additional pair of cross-car andfore/aft position detecting apparatuses 116 are mounted to opposed floorstanchions 122, between which the vehicle body is stationed. Theposition detecting apparatuses 116 are preferably PERCEPTRON robotguidance sensors, which are well-known in the art and are exemplified inU.S. Pat. No. 4,645,348, which is incorporated by reference herein. Inbrief, each position detecting apparatus 116 includes a light source,such as a laser diode, that is modified to generate a structured lightpattern for illuminating target locating features on a target object.The structured light pattern is preferably projected onto the targetlocating features at an angle that is normal to the target feature. Asdefined herein, a locating feature is equivalent to a locating point orsurface. A sensor device within the position detecting apparatus 116receives a reflected light image through a set of sensor optics, such asphoto-diodes, which transduce the reflected light image into electricalsignals whose signal values are approximately proportional to theintensity of the incoming light. Each position detecting apparatus 116is calibrated in reference to known X, Y, and Z Cartesian coordinatehardpoints within the workstation, such as the vehicle body locator pins114. Calibration and setup methods are well known in the art and areexemplified by U.S. Pat. No. 4,841,460, which is incorporated byreference herein. Also, calibration and setup procedures may be carriedout using AUTOCAL or DYNACAL, available from Dynalog, Inc. of BloomfieldHills, Mich.

[0082] Referring now to FIG. 14, there is provided an illustration ofone embodiment of the present invention in block diagram form. Theposition detecting apparatuses 116 are all coupled to the machine visioncontroller 118, which processes electro-optical signals from theposition detecting apparatuses 116. The machine vision controller 118compares the received electro-optical signals to calibration referencedata to yield actual X, Y, and Z Cartesian coordinate data that arerepresentative of the actual as built location of the target locatingfeatures.

[0083] The machine vision controller 118 is also coupled to a centralprocessor 124, which executes a predefined best-fit algorithm on thecoordinate data from the machine vision controller 118. It iscontemplated that the central processor 124 could be incorporated withinthe machine vision controller 118 and need not be a separate device. Inany case, the central processor 124 includes a controller 126, memory128, and interface electronics 130. The interface electronics 130 mayconform to protocols such as RS-232, parallel, small computer systeminterface, and universal serial bus, etc. The memory 128 can be RAM,ROM, EPROM, and the like. The controller 126 may be configured toprovide control logic that provides output instructions. In thisrespect, the controller 126 may encompass a microprocessor, amicro-controller, an application specific integrated circuit, and thelike. The controller 126 may be interfaced with an additional memory 132that is configured to provide storage of computer software that providesthe best-fit algorithm and that may be executed by the controller 126.Such memory 132 may also be configured to provide a temporary storagearea for data received by the central processor 124 from the machinecontroller 118.

[0084] Using the predefined best-fit algorithm, the function of thecentral processor 124 is to calculate an actual as built vehicle bodyreference feature of some type, such as an actual vehicle bodycenterline or gridline, or an actual vehicle Cartesian coordinate map orwireframe, and the like. The best-fit algorithm determines an imprecisedistance between as built features and design-intent locations anddivides such distance in half to establish the new gridlines orcenterlines for the actual body-in-white in the as built conditionthereby reducing the error of the location of such feature by one-halffrom its design-intent-location. In the previous embodiment, such“calculation” was carried out by mechanical floating sockets and amechanical lever and crank mechanism. One example of the best-fitalgorithm can be better understood with reference to FIGS. 15 and 16,which illustrate conceptual representations of the vehicle body A.

[0085]FIG. 15 illustrates a conceptual view of the top of the vehiclebody A wherein a design-intent locating feature B_(L) represents apoint, surface, or the like on a left side of the vehicle body A anddesign-intent locating feature B_(R) represents a point, surface, or thelike on the right side of the vehicle body A. The features B_(L), B_(R)are preferably located symmetrically cross-car and may consist of hingemounting points on A-pillars, leading edges of doors that are alreadymounted to the vehicle body A, and the like. Actual locating featuresB′_(L) and B′_(R) are misaligned or displaced from the design-intentlocating features B_(L) and B_(R) (as shown in exaggeration for clarity)due to tolerable dimensional variances of the actual vehicle body from atheoretical design-intent vehicle body, such as those variances inducedby framing and welding stations upstream from the workstation.

[0086] Datum D_(x) is a centerline created through design-intentlocating features B_(L) and B_(R). Similarly, datum O_(y) is acenterline through design-intent locating feature B_(L) that is parallelto the theoretical centerline D_(y) of the theoretical design-intentvehicle body. The terms datum, centerline, and net reference feature areused herein interchangeably because all commonly relate to things fromwhich other coordinates are referenced. Moreover, the term centerline isequivalent to the terminology median feature, median point, or mediansurface. In any case, datums D_(x) and O_(y) intersect to define atheoretical Cartesian origin from which the locations of the actuallocating features B′_(L), B′_(R) can be referenced. The actual locatingfeatures B′_(L) and B′_(R) each have X and Y Cartesian coordinatescomponents, wherein actual locating feature B′_(L) includes componentsX_(L) and Y_(L), while actual locating feature B′_(R) includescomponents X_(R) and Y_(R). Thus, the amount of error due to processingevents can be measured and the locations of the actual locating featuresB′_(L) and B′_(R), can be determined by mathematical reference to thedatums D_(x) and O_(y). Similarly, the location of a longitudinalcenterline N₁ of the actual as built vehicle body can be calculated byaveraging the Y components of the actual as built locating featuresB′_(L) and B′_(R). Expressed as an equation, this calculation amounts to(Y_(L)+Y_(R))/2. Expressed as a concept, the calculation amounts tobalancing out the locational errors of two features, between thefeatures, to create a best fit condition regardless of previous built-invehicle body errors. Also, location of a fore-aft centerline N₂ of theactual as built vehicle body can be calculated by averaging the Xcomponents of the actual locating features B′_(L) and B′_(R). Expressedas an equation, this calculation amounts to (X_(L)+X_(R))/2. It iscontemplated that the present invention could use multiple of specificactual locating features along each side of the vehicle body A toprovide even higher accuracy for developing the net reference featuressuch as centerlines and the like for the attachment of components to theas built body-in-white after framing and welding operations arecompleted.

[0087] Like FIG. 15, FIG. 16 represents a conceptual view of the vehiclebody A, but from the front of the vehicle body A looking rearward.Design-intent locating feature C_(L) represents a point, surface, or thelike on a right side of the vehicle body A, and design-intent locatingfeature C_(R) represents a point, surface, or the like on the left sideof the vehicle body A. The design-intent locating features C_(L), C_(R)are preferably located symmetrically opposed and may be points orsurfaces on a motor compartment cross-member, a radiator rail, or thelike. Actual locating features C′_(L) and C′_(R) are misaligned ordisplaced as a result of processing from the design-intent locatingfeatures C_(L) and C_(R) due to tolerable dimensional variances of theactual vehicle body, such as those variances induced by upstream framingand welding stations.

[0088] Datum D_(z) is a centerline created through design-intentlocating features C_(L) and C_(R). Datum D_(z) defines a theoreticalone-dimensional origin from which the locations of actual locatingfeatures C′_(L) and C′_(R) can be determined. The actual locatingfeatures C′_(L) and C′_(R) each have Z Cartesian components. Actuallocating feature C′_(L) includes component Z_(L), while actual locatingfeature C′_(R) includes component Z_(R). Thus, the locations of theactual locating features C′_(L) and C′_(R), can be calculated bydimensional reference back to datum D_(z). Similarly, the location of atheoretical up/down net locating line or centerline N₃ of the actualvehicle body A can be calculated by averaging the Z components of theactual locating features C′_(L) and C′_(R). Expressed as an equation,this calculation amounts to (Z_(L)+Z_(R))/2. Expressed as a concept, thecalculation amounts to balancing out any locational error between twolocating features points in the Z coordinate direction to create abest-fit condition regardless of previous built-in vehicle body errorsand regardless of the design-intent locations.

[0089] It is contemplated that the present invention may include othermore complex methods of establishing the locations of the targetlocating surfaces B′_(L) and B′_(R) and the adjusted net referencefeatures or centerlines N₁, N₂, and N₃ that they establish. For example,the central processor may store a predefined design-intent wireframedata model that has millions of X, Y, Z Cartesian coordinate data pointsthat represent the surface contours of a design-intent vehicle body. Thedesign-intent wireframe data model may also include reference datums,from which the locations of actual locating features can be referencedon a coordinate-by-coordinate basis. The wireframe data model can beoffset from its design-intent condition, to a wireframe representationof the actual vehicle body as sensed by the position sensingapparatuses. In other words, the position sensing apparatuses canestablish a relatively small amount of actual vehicle body coordinates,which can be established as datum points relative to the design-intentwireframe data model so as to replace corresponding data points in thedesign-intent wireframe data model. Then, the controller can run aprogram to adjust, or pull, all of the remaining design-intent ordesign-intent grid data points into correspondence with the actual datapoints to reestablish a new as built grid system for each entire vehiclebody after it is processed past the framing/welding station. In otherwords, the few actual vehicle body coordinates can be extrapolated inreference to the wireframe data model reference datums to generateactual wireframe data of the actual vehicle body coordinates. From theactual wireframe data, vehicle body centerlines, or any other types ofreference features, can be generated.

[0090] Referring again to the block diagram of FIG. 14, a robotcontroller 134 receives the output instructions from the centralprocessor 124 and thereby renders movement instructions to robots 136,such as NACHI SC300F robots. The present invention adjusts the robots136 with respect to newly established net best fit reference features orcenterlines N₁, N₂, and N₃ created by averaging out the distancesbetween actual as built locating features. The net effect of suchaveraging results in reducing overall dimensional deviation fromdesign-intent by one-half, as well as to establish an actual netlocation of the as-built vehicle body, and use the newly established netlocating centerlines N₁, N₂, and N₃ from which to adjust positions ofthe robots 136 and associated tooling components so that new net targetattachment points can be more easily and accurately provided on thevehicle body A to enable the attachment of components thereto withoutthe need for oversized attachment holes and slip planes. The robots 136use the new net locating centerlines N₁, N₂, and N₃ to locate relativethereto and perform work at new, adjusted target work locations. Under atheoretically perfect design-intent condition, the robots wouldreference the design-intent centerlines or datums D_(x), D_(y), D_(z),O_(y) of the vehicle body and move predefined distances therefrom totarget coordinates proximate the work to be performed on the vehiclebody. Instead, however, the robots reference the adjusted or actual asbuilt centerlines or net locating lines N₁, N₂, and N₃ and then move thepredefined distances therefrom to target coordinates or positions tocreate attachment points, holes or pads where outer body components canbe associated to, without the need of any labor to make final fitadjustments to the panel.

[0091] Referring again to FIG. 13, the robots 136 each preferablyinclude end-effectors or tooling 138 of some kind, such as form andpierce tooling, or form and clinch tooling exemplified by currentlypending U.S. patent application Ser. Nos. 10/641,580 filed Aug. 15, 2003and 10/329,893 filed Dec. 26, 2002 which are assigned to the assigneehereof and are all incorporated by reference herein. The presentinvention, however, is not limited to use with the above-describedtooling 138 and may include any devices including, but not limited to,gauges, measuring devices, welders, lasers, sprayers, and the like. Inaccordance with the preferred embodiment, the robot tooling 138 createsattachment features for various vehicle outer body panels,sub-assemblies, and other components that are to be attached to thevehicle body in a downstream station from the framing/welding station.

[0092] As a result of balancing out the created processing or inherentdimensional errors of the vehicle body, all attachment features createdby the robot tooling 138 are net located with respect to the newlyestablished net reference centerlines N₁, N₂, and N₃ (or other types ofX, Y, Z net reference features). Furthermore, the present inventionessentially creates a best fit attachment feature and completelyeliminates the need to provide for a slip plane in order to attach acomponent to the vehicle body A. Therefore any outer body component,i.e. hood, fender, doors, decklid, liftgate, front bumper, rear or frontfacia, tail-lights, etc. being attached to the body-in-white can befabricated with an attachment feature at net or design-intent locationssince they will be attached to a best fit or net-formed, attachmentfeature on the vehicle body.

[0093] A method of the present invention is provided for assemblingobjects to a body A. The first step involves moving the body A, havingtarget or actual locating features B′_(L), B′_(R), C′_(L), C′_(R)thereon, into an approximate location. The approximate location ispreferably established by the hard point locator pins 114 of theworkstation 110 that engages the preformed setup locating features ofthe body A and these locations are read into a microprocessor.

[0094] Thereafter, the actual as built locating features B′_(L), B′_(R),C′_(L), C′_(R) are engaged with the position detecting apparatuses 116and the position detecting apparatuses 116 are immobilized or the actuallocation of these features are read into a microprocessor. The termengaging is broadly defined to include interacting or operating upon,and the position detecting devices 116 are immobilized by the stanchions122 and overhead support 120.

[0095] The third step involves determining an imprecise distance betweenthe actual locating features B′_(L), B′_(R), C′_(L), C′_(R) of the bodyA in one or more of X, Y and Z directions of a Cartesian coordinatesystem. In other words, the method establishes the actual location oflongitudinal and lateral locating features on the body A to establish anactual coordinate system for the as-built body.

[0096] The fourth step involves creating a median of the imprecisedistance, to define net reference features N₁, N₂, N₃ at the median. Inother words, the method of the present invention balances out oraverages the locations of the actual locating features B′_(L), B′_(R),C′_(L), C_(R) to establish actual vehicle body centerlines, or other netas built reference features.

[0097] The fifth step involves locating robot tooling 138 with respectto the net reference features N₁, N₂, N₃ adjacent the body A. In otherwords, the method of the present invention adjusts the location ofcertain attachment point tooling from a nominal tooling location to are-configured target tooling location that is based on the as builtactual centerlines or as built net reference features.

[0098] The sixth step involves performing work on the body A toestablish a net attachment feature on the body A for assembling anobject at the net attachment feature location. In other words, themethod of the present invention effectively reforms a body surface tocreate an attachment feature to a design-intent location for such anattachment feature. Thus all attachment points are net-formed todesign-intent.

[0099] The method of the present invention may be performed as acomputer program and the various Cartesian coordinate data may be storedin memory as a look-up table, wireframe model, or the like. The computerprogram may exist in a variety of forms both active and inactive. Forexample, the computer program can exist as software program(s) comprisedof program instructions in source code, object code, executable code orother formats; firmware program(s); or hardware description language(HDL) files. Any of the above can be embodied on a computer readablemedium, which include storage devices and signals, in compressed oruncompressed form. Exemplary computer readable storage devices includeconventional computer system RAM (random access memory), ROM (read onlymemory), EPROM (erasable, programmable ROM), EEPROM (electricallyerasable, programmable ROM), and magnetic or optical disks or tapes.Exemplary computer readable signals, whether modulated using a carrieror not, are signals that a computer system hosting or running thecomputer program can be configured to access, including signalsdownloaded through the Internet or other networks. Concrete examples ofthe foregoing include distribution of the graphics display classes,their extensions, or document-producing programs on a CD ROM or viaInternet download. In a sense, the Internet itself, as an abstractentity, is a computer readable medium. The same is true of computernetworks in general. It is therefore to be understood that the method ofthe present invention may be performed by any electronic device capableof executing the above-described functions.

[0100] This embodiment of the present invention is an improvement overprior art techniques of assembling components to a body. Many prior arttechniques involve developing correction data at each individualassembling position for individual components to be attached to a body.In other words, prior art techniques require calculating the mountinglocations for a vehicle body on a component-by-component basis, suchthat the mounting of each component must be separately, individuallyadjusted. Such a process is time-consuming, complex, and ultimately notas desirable as the present invention since such prior art techniquesstill usually require the use of slip-planes to adjust the mounting ofbody components.

[0101] Instead the present invention provides apparatus and techniquesfor balancing out misalignment of component attachment features betweenposition detecting apparatuses to generate new centerlines or netreference features of the vehicle at half the distance of overalldeviation of the individual component attachment features. This avoidsthe inferior prior art process of individually recalculating theassembling positions for each body member to be attached to a vehiclebody at a specific location. Accordingly, the present invention is moreaccurate as effective compared to the prior art, because the presentinvention uses a best-fit algorithm to net-form attachment features ofthe total vehicle at design-intent coordinates, regardless ofmisalignments due to processing through the framing/welding station ofthe vehicle body. As is clear to a person skilled in the prior art theconcept can easily be adapted to a specific intent application such asfitting a pivotable window into a window opening in the vehicle body. Toaccomplish a best fit assembly position of the hinges for the window.

[0102] The invention including the method and apparatus as heretoforeset forth may be embodied in other specific forms without departing fromthe spirit or essence of the invention. The presently disclosedembodiments are, therefore, to be considered in all respects asillustrative and not as a restriction on the invention, the scope of theinvention being indicated by the appended claims. Rather the foregoingdescription and all changes that come within the meaning and range ofequivalency of the claims are to be embraced therein.

What is claimed is:
 1. An apparatus for creating net attachment featureson a three-dimensional object defined by X, Y and Z Cartesiancoordinates, said apparatus comprising: a three-dimensional body havingone end and an opposite end, each end of said body having at least oneprimary locating point thereon, said at least one primary locating pointselectively located within a known tolerance range with respect to saidX, Y and Z directions of said Cartesian coordinate system; means forstoring design-intent locations of selective primary locating points onsaid three-dimensional body defined by X, Y and Z Cartesian coordinates;means for establishing the actual location of said at least one primarylocating point on said body, in each of said X, Y and Z directions, saidexact location being defined as a datum position; means for comparingsaid actual location of said at least one primary locating point on saidbody with said design-intent location of said at least one primarylocating point in said means for storing in each of said X, Y and Zdirections, said comparing means further comprising: microprocessormeans for determining an imprecise distance in each of said X, Y and Zdirections between said actual location of said at least one primarylocating point with said design-intent location; and means for creatinga median point of said imprecise distance in each of said X, Y and Zdirections, said median point of said imprecise distance on said atleast one primary locating point of said body creating an adjusted netposition of said at least one primary locating point in each of said X,Y and Z directions on said body; and means for directing at least oneprogrammable work performing device to said adjusted net positionwhereby said work performing device performs work on said body such thatat least one adjusted net attachment location is established for objectsto be attached to said body.
 2. A master locating apparatus forestablishing a plurality of net attachment features on an impreciselyconstructed three-dimensional body structure of unknown dimensionalaccuracy within a known tolerance range, relative to an X, Y and ZCartesian coordinate system, said imprecisely constructedthree-dimensional body structure adapted for attachment of one or moreexternal members, said apparatus comprising: at least one columnarmember located adjacent said body; at least two programmable positiondetecting apparatuses attached to said at least one columnar member,said at least two programmable position detecting apparatuses furtherbeing located in spaced apart relation on opposing sides of said bodystructure, each of said at least two programmable position detectingapparatuses further comprising: programmable means for visually engagingsaid body structure at least one predetermined primary locating point toestablish an actual location in at least two-dimensional planes of saidthree-dimensional body structure, said programmable means for visualengaging said body structure located alongside said body structure;means for storing design-intent locations of selective primary locatingpoints on said three-dimensional body structure defined by X, Y and ZCartesian coordinates; microprocessor means for comparing said actuallocation of said predetermined primary locating point in said at leasttwo-dimensional planes with design-intent locations of said at least onepredetermined primary locating point in each of said at leasttwo-dimensional planes to establish an imprecise distance in each ofsaid two-dimensional planes between said actual location and saiddesign-intent location in each said two-dimensional planes; means forcreating a median point of said imprecise distance between said actuallocation found by said programmable visual engaging means for each ofsaid two-dimensional planes and said design-intent location, said medianpoint of said imprecise distance in each of said two-dimensional planesdefining an adjusted net location; and means for communicating saidadjusted net location to a work performing tool whereby said workperforming tool performs work on said body structure with respect tosaid adjusted net location.
 3. A method for assembling objects to athree-dimensional body, said method comprising the steps of: moving saidbody having one end and an opposite end into a fixtured location, saidbody having at least one primary locating point thereon, visuallyengaging said at least one primary locating point of one end of saidbody with at least one position detecting apparatus reading the actuallocation of said at least one primary locating point, said locationbeing defined by X, Y and Z Cartesian coordinates; storing design-intentlocations of selective primary locating points on said three-dimensionalbody defined by X, Y and Z Cartesian coordinates into a microprocessor;determining an imprecise distance between said at least one primarylocation point of said one end of said body in each one of X, Y and Zdirections of said Cartesian coordinate system and said storeddesign-intent data location for said at least one primary locatingpoint; creating a median point of said imprecise distance, said medianpoint defining a new adjusted net position at said median point of saidimprecise distance; locating at least one work performing tool withrespect to said new adjusted net position adjacent said body; andperforming work on said body to establish a net attachment feature onsaid body for assembling at least one object at said net attachmentfeature of said body.
 4. A master locating apparatus mounted alongsideof the direction of travel of an assembly line for a three-dimensionalbody structure of unknown dimensional construction within a knowtolerance range, said master locating apparatus comprising: at least twocolumnar members in spaced apart relationship on opposite sides of saidassembly line; a support member having respective ends, one of said endsattached to one of said at least two columnar members, the other side ofthe said ends attached to the other of said at least two columnarmembers; at least two position detecting apparatuses located in spacedapart relations on opposite sides of said assembly line to permit saidassembly line to pass therebetween, each of said at least two positiondetecting apparatuses further having: means for visually engagingopposite sides of said three-dimensional body structure at a pluralityof preselected defined locations to establish a datum position in atleast two-dimensional planes of said three-dimensional body structure oneach side of said three-dimensional body structure when said bodystructure is between said engagement means, said means for visuallyengaging located alongside said assembly line and visually engaging saidbody structure at said plurality of preselected defined locations toestablish an imprecise distance in at least one of said two-dimensionalaxes between said datum position on one side of said three-dimensionalbody structure and said datum position on said opposing side of saidthree-dimensional body structure; and means for establishing a mediandistance point of said imprecise distance between said datum position onsaid one side and said datum position on said opposing side of saidthree-dimensional body structure in said at least one of saidtwo-dimensional planes, said median distance defining an adjusted netposition of said three-dimensional body structure; and means forperforming work on said three-dimensional body structure with respect tosaid adjusted net position.
 5. An apparatus for creating net attachmentfeatures on a three-dimensional object defined by X, Y and Z Cartesiancoordinates, said apparatus comprising: a three-dimensional body havingat least one primary locating feature thereon; means for establishing anexact location of said at least one primary locating feature in each ofsaid X, Y and Z Cartesian coordinates; means for calculating animprecise distance between said at least one primary locating feature;means for creating a median of said imprecise distance, said median ofsaid imprecise distance defining an adjusted net reference feature; andmeans for locating at least one work performing device with respect tosaid adjusted net reference feature, whereby work performed on said bodyestablishes at least one adjusted net attachment feature location forobjects to be attached to said body.
 6. The apparatus as claimed inclaim 5, further comprising means for net-forming surfaces of said bodyat design-intent coordinates for said objects.
 7. A method forassembling objects to a body, comprising the steps of: moving a bodyhaving locating features thereon into an fixtured location; engagingsaid locating features with position detecting apparatuses; determiningan imprecise distance between the locating features of the body in oneor more of X, Y and Z directions of a Cartesian coordinate system;creating a median of the imprecise distance to define a net referencefeature; and locating robot tooling with respect to said net referencefeature.
 8. The method as claimed in claim 7, further comprising thestep of net-forming at least one attachment feature on said body forassembling an object to said at least one net attachment feature.
 9. Theapparatus claimed in claim 4, wherein said means for establishing theexact location of said at least one primary locating point on each endof said body further comprising a front and rear gantry straddling aproduction line such that said body can pass through thereunder.
 10. Theapparatus claimed in claim 4 further comprising: means for establishingthe exact location of said at least one primary locating point on eachend of said body comprises a first plurality of position detectingapparatuses, at least two of said first plurality of position detectingapparatuses being disposed on opposing sides of said body.
 11. Theapparatus claimed in claim 4, wherein each of said first plurality ofposition detecting apparatuses each include a laser.
 12. The apparatusclaimed in claim 4, wherein said means for establishing a mediandistance of said imprecise distance further comprises a microprocessor.13. The apparatus claimed in claim 10, wherein said means forestablishing the exact location of said at least one primary locatingpoint on each end of said body comprises a second plurality of positiondetecting apparatuses each having a laser sensor, at least two of saidsecond plurality of position detecting apparatuses being disposed onopposing sides of said body.
 14. The apparatus claimed in claim 1,wherein said body comprises a welded body-in-white.
 15. The apparatusclaimed in claim 2, wherein said at least one columnar member comprisesa front and rear gantry straddling a production line such that said bodystructure can pass through thereunder.
 16. The apparatus claimed inclaim 15, wherein each of said at least two position detectingapparatuses each have a laser thereon.
 17. The apparatus claimed inclaim 16, wherein said means for creating a median point of saidimprecise distance comprises a microprocessor.
 18. The apparatus claimedin claim 15, wherein said at least two position detecting apparatusescomprises a first pair of position detecting apparatuses disposed onopposite sides of said body structure, and a second pair of positiondetecting apparatuses disposed on opposite sides of said body structure,each of said second pair of position detecting apparatuses having asecond laser sensor thereon thereto.
 19. The method according to claim 3further comprising the step of assembling and welding said body prior tothe step of engaging said at least one primary locating point such thatminimal additional variation is introduced after the position of said atleast one primary locating point is established.
 20. The methodaccording to claim 3, wherein the step of visually engaging said atleast one primary locating point comprises the step of providing each ofsaid at least one position detecting apparatus with a laser sensor,whereby one of said laser sensors visually engages said at least oneprimary locating point to establish two of said X, Y, and Z directions,and the second of said laser visually engages said at least one primarylocating point to establish the third of said X, Y and Z directions. 21.The method according to claim 20, wherein the step of visually engagingsaid at least one primary locating point of each said end of said bodywith at least one position detecting apparatus comprises the step ofvisually engaging a first pair of primary locating points on said oneend of said body with a first pair of position detecting apparatusesdisposed on opposite sides of said body, and visually engaging a secondpair of primary locating points on said opposite end of said body with asecond pair of position detecting apparatuses disposed on opposite sidesof said body.
 22. The method according to claim 20, wherein the step ofcreating a median point of said imprecise distance comprises the step ofproviding a microprocessor to receive data from said step of visuallyengaging said at least one primary locating point on each end of saidbody and comparing said data with design-intent positions stored in saidmicroprocessor to generate said median point of said imprecise distance.23. The method according to claim 20, wherein the step of locating atleast one programmable work performing tool with respect to said newadjusted net position further comprises the step of communicating saidmedian point to said work performing tool.
 24. The apparatus claimed inclaim 4, wherein said three-dimensional body structure comprises awelded body-in-white.
 25. The apparatus claimed in claim 4, wherein saidat least two columnar members comprise a front and rear gantrystraddling a production line such that said three-dimensional bodystructure can pass through thereunder.
 26. The apparatus claimed inclaim 2, wherein said at least two position detecting apparatusescomprises a first pair of position detecting apparatuses disposed onopposite sides of said body structure, and a second pair of positiondetecting apparatuses disposed on opposite sides of said body structure,each of said second pair of position detecting apparatuses having alaser mounted thereto.